The present invention is related to a serial fan, and more particularly to an axial-flow fan with a plurality of rotor vanes connected in series in a single fan guard.
The axial-flow fan is a popular fan device which has the features of a simple structure, low cost, and a high airflow rate. Therefore, it has been widely used in various systems as an air conditioning or ventilating device, for instance, as a ventilation fan in a computer system.
Generally, in order to avoid the interruption of operation due to the breakdown of fans, a set of standby fan system is usually provided and connected with the original fan system in series to prevent the system or device from being damaged. Moreover, because the total pressure of the axial-flow fan is relatively low, the axial-flow fan cannot fully develop a high airflow rate in a system of a high resistance. Thus, in the case that a high total pressure is needed, two or more axial-flow fans are connected in series to provide the high total pressure.
Typically, a so-called serial fan is constituted by two independent fan units assembled through a specific circuit design. Each fan unit includes a fan guard and a rotor device. As shown in FIG. 1, the first fan unit is constructed by a fan guard 13 and a rotor device including a motor 11, and a rotor vane 12 having a shaft ring 121 connected to the motor 11 and a plurality of blades 122 fixed on the circumferential surface of the shaft ring 121. Likewise, the second fan unit is constructed by a fan guard 16 and a rotor device including a motor 14, and a rotor vane 15 having a shaft ring 151 connected to the motor 14 and a plurality of blades 152 fixed on the circumferential surface of the shaft ring 151. After the first and second fan units are assembled respectively, both of them are coupled together through screws (not shown), thereby completing the construction of the serial fan. However, such a design is more complicated and needs more time and manufacturing cost in the assembly of this serial fan.
In fact, according to the above description, it can be found that the conventional serial fan is constructed by two independent fan units connected in series. However, the serial connection of two fan units can not guarantee that the total pressure of the airflow discharged from the fan can be doubled. Even if only one fan operates and the other still stays as a standby fan, the latter will reduce the total pressure in operation because the resistance between both of them is increased, thereby decreasing their operating efficiency. For example, when the airflow flows through these two fan guards 13, 16 having the structures as shown in FIG. 1 and as described, the airflow will encounter a plurality of ribs 131, 161, thereby resulting in the generation of turbulent flows and an adverse effect on the blast pressure enhancement. Consequently, the heat-dissipating efficiency of the fan is reduced. Thus, in certain situations, the two axial-flow fans connected in series are separated far apart to minimize the interference between them. Nevertheless, this way can not be applied in the case that the space is limited.
Therefore, it is desirable to develop an axial-flow serial fan with a plurality of rotor vanes that only occupies a small space, has a simplified structure, and can effectively eliminate the interference between two fans.
An object of the present invention is to provide a serial fan which can be assembled easily, fastly and conveniently, and has a strengthened bonding structure.
Another object of the present invention is to provide an axial-flow fan having a plurality of rotor vanes connected in series in a single fan guard, which can effectively eliminate the interference between fans.
According to the present invention, the serial fan includes a main frame, a plurality of rotor vanes connected in series within the main frame along an axial direction of the serial fan, a first support disposed inside and connected with the main frame for supporting one of the plurality of rotor vanes, and a second support detachably connected with the first support for supporting another one of the plurality of rotor vanes.
In accordance with one aspect of the present invention, the first support includes a first engaging member disposed on a base thereof and the second support includes a second engaging member disposed on a base thereof to be engaged with the first engaging member for tightly assembling the first support and the second support together. The first engaging member includes a plurality of retaining grooves formed on the base of the first support and the second engaging member includes a plurality of hook structures to be received by the plurality of retaining grooves, respectively. Certainly, the structure of the first engaging member can be exchanged with that of the second engaging member.
In addition, the base of the first support has a flange and the base of the second support has an outwardly extended peripheral wall, the outer diameter of which is slightly smaller than the inner diameter of the flange of the first support such that the bases of the first and second supports are engaged with each other. Alternatively, the base of the second support has a flange and the base of the first support has an outwardly extended peripheral wall, the outer diameter of which is slightly smaller than the inner diameter of the flange of the second support such that the bases of the first and second supports are engaged with each other.
In accordance with another aspect of the present invention, the serial fan further includes a plurality of motors respectively received by the first and second supports for driving the plurality of rotor vanes to rotate.
Preferably, the serial first support has a base and a hollow cylinder substantially located at a center of the base for receiving one of the plurality of motors and the one of the plurality of rotor vanes. Likewise, the second support also has a hollow cylinder substantially located at a center of a base thereof for receiving another one of the plurality of motors and another one of the plurality of rotor vanes. The second support can be made of plastic or metal.
In accordance with another aspect of the present invention, the first support is connected with the main frame through a plurality of guard blades radially arranged inside the main frame and fixed onto an inner surface of the main frame by each end thereof. Each of the plurality of guard blades has a shape substantially identical to that of each blade of the plurality of the rotor vanes for enhancing a heat-dissipating efficiency. Preferably, the first support, the main frame and the plurality of guard blades are integrally formed together and can be made of plastic and metal, respectively.
In another preferred embodiment of the present invention, the serial fan further includes a separator for preventing a magnetic field interference between two adjacent motors. The separator can be disposed between one of the first and second supports and one of the plurality of motors, or between the first support and the second support, Preferably, the separator is a metal plate. More preferably, the separator is an adhesive tape containing a metallic component to be directly attached to a base of the first support or the second support.
The present invention may best be understood through the following description, with reference to the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and in which: